This application relates to gas pressure operated dispensing containers for automatically discharging viscous liquids such as sealants, caulking materials, adhesives, and pastes.
Viscous liquids for consumer use, such as room temperature moisture-curable liquid rubber, particularly room temperature moisture-curable silicone sealants, are commonly marketed in gas pressure operated dispensing containers. Such containers generally contain the viscous liquid in a collapsible compartment surrounded by a pressure chamber containing compressed gas inside a rigid canister. The outlet of the bag is fitted with a discharge valve via a collapse-preventing rigid ring. Upon manual activation of the valve the gas pressure forces collapse of the compartment and forces the viscous material from the bag through the valve to dispense the material.
In the filling and use of such dispensing containers it has been found that certain problems are encountered with present commercially used configurations. For example, it has been found that in the filling operation when the rigid ring and discharge valve are installed in the outlet of the collapsible compartment air may become entrapped in the compartment between the bottom of the discharge valve and the surface of the liquid to be dispensed. This may result in the formulation of air bubbles in the cured material. Obviously if the dispensed material is a sealant, porosity can result in an ineffective seal. Furthermore, if the material being dispensed is moisture-curable the entrapped air may contain sufficient moisture to cause curing in the container of at least a surface layer of the material, resulting at times in plugging of the valve, thereby rendering the container and its contents useless.